Eight million people living in and around Tehran. In the past years and decades, the number of inhabitants in the Region is grown around the Iranian capital – and with it, the demand for water.

the massif is also the number of wells that were drilled for the supply is increased: While there were in 1968, only about 4000 of them, were it 50 years later, more than eight times as many. This, in turn, that the ground water level decreases in the Region around Tehran – and in the time between 1984 and 2011, the Minus amounted to twelve meters.

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researchers at the German research centre for Geosciences GFZ in Potsdam have investigated the effect now. For that purpose they used the data from four different satellites: the now operational European “Envisat”, the now silent Japanese “Daichi”, the German “TerraSAR-X” and the European “Sentinel-1”.

From which the data was generated the image above. In the blue coloured areas of the floor is not lowered, in red especially. “Sentinel-1” delivered since 2014 first of all the 24 days of fresh, high-resolution radar images of this region of the world, since in 2016, even all the twelve days. “As a result, it is possible to analyze geological risks such as land subsidence, almost in real time,” explains GFZ researcher Mahdi Motagh.

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Together with his colleague, Mahmud Haghshenas Haghighi, he reported that just in the journal “Remote Sensing of Environment”, that some areas around Tehran in the period between 2003 and 2017, to more than 25 inches per year have been lowered. A total of several meters came along. The lead, among other things, to columns in the soil and cracks in building walls.

The scientists warn that some of the groundwater basin through the exploitation had even been damaged irreversibly. They could not store as much water as before. Scientifically-based plans for water management could help the Situation, but defuse it, so the two researchers.

One of the reasons for the strong stress on the natural water storage under the ground is the attempt on the part of Iran to be in the food supply for independent. This leads on the one hand, that the groundwater basins are exploited to. On the other hand, it ensures that you will fill properly again – because the water is held in dams back, and it can seep through the soil.

chs.

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